Blue-Green Algae Bloom Updated to include Hammell’s Bay – September 2, 2022

The Simcoe Muskoka District Health Unit (SMDHU) is informing residents and visitors to the Township of Muskoka Lakes that laboratory analysis has confirmed the presence of a blue-green algae bloom impacting Hammell’s Bay, Three Mile Lake, Township of Muskoka Lakes. As a result, the blue-green algae notice issued August 29, 2022 for the Carlo Enterprise Road and Cowan Park Road, Utterson is being expanded to include all of Three Mile Lake and Hammell’s Bay, Township of Muskoka Lakes.

Many species of blue-green algae (also called cyanobacteria) have the potential to produce toxins that are harmful to the health of humans and animals when exposed in large amounts. Due to the confirmed presence of the bloom, we are asking residents and visitors to exercise caution and recognize that toxins may also be present.

As a precautionary measure, the SMDHU urges residents and businesses to avoid drawing or drinking water from private water supplies that are impacted by the lake where blue-green algae has been identified and to take the following precautions:

  • Do not use a private water supply that is impacted or draws water from this area of the lake for the preparation of infant formula.
  • Do not allow pets or livestock to drink or swim in the water where an algae bloom is visible.
  • Fish taken from waters with cyanobacterial blooms have the potential to contain toxins. Exercisecaution when eating fish caught in water where blue-green algae blooms occur.
  • Do not use herbicides, copper sulphate or other algaecides that may break open algae cells and release toxins into the water.
  • Avoid water sport activities where an algae bloom is visible.

I strongly recommend seeking medical attention if symptoms such as skin, eye or throat irritation, allergic reactions or breathing difficulties occur following contact with the blue-green algae bloom. Anyone who comes into contact with blue-green algae should wash with soap and water or rinse thoroughly with clean water. Swimming, bathing or showering with water not visibly affected by a blue- green algae bloom is not expected to cause health effects.

The health unit and the Ministry of Environment, Conservation and Parks will continue to work together to monitor the algal bloom and updates will be provided on our website

For further information, call Health Connection Monday to Friday 8:30 a.m. to 4:30 p.m. at 1-877-721- 7520. Links to general information and updates about blue-green algae are available on the health unit website at


Charles Gardner, MD, CCFP, MHSc, FRCPC Medical Officer of Health